Shared Tributaries of the Tigris River

Executive Summary

The Tigris River Basin has several sub-basins that are shared between Iraq and Turkey or between Iran and Iraq. The main shared tributaries are the Feesh Khabour, the Greater Zab, the Lesser Zab and the Diyala.

With more than 27 BCM, the Tigris tributaries significantly contribute to total Tigris river flow. The main contribution to discharge originates from the Greater and Lesser Zab Rivers, which contribute 40-60% of total Tigris flow in Baghdad. In general, the four shared tributaries exhibit similar flow regimes, with normal fluctuations of wet and dry years around the mean annual flow. Although the Lesser Zab and the Diyala have been dammed since the 1960s, there is currently no evidence of a regulated stream-flow regime.

Water resources management differs from one shared basin to another. While the Greater Zab is to date unregulated, several of the dams and regulators on the Lesser Zab and the Diyala support irrigated agriculture projects in the region. No specific water agreements govern any of the four tributaries.

The Lesser Zab in Bekhme, Iraq, 2005. Source: Ed Kashi/VII.

The Greater Zab River, at Zahko, Iraq, 2012. Source: James Gordon.

Irrigation canal near the town of Taweela in the Diyala Basin, Iraq, 1992. Source: Ed Kashi/VII.

The Greater Zab in Bekhme, Iraq, 2005. Source: Ed Kashi/VII.

Basin Facts

River

Feesh Khabour

Greater Zab

Lesser Zab

Diyala

Basin Area Shares

Iraq 43%Turkey 57%

Iraq 65%Turkey 35%

Iran 24%Iraq 76%

Iran 25%Iraq 75%

Basin Area

6,143 km2

26,310 km2

19,780 km2

33,240 km2

River Length

181 km

462 km

302 km

574 km

Mean Annual Flow Volume

2 BCM

12.7 BCM

7.8 BCM

4.6 BCM

Dams

Unregulated to date

Unregulated to date

2 (~7 BCM capacity)

4 (>7 BCM capacity)

Projected Irrigated Area

~37,000 ha

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The Inventory of Shared Water Resources in Western Asia is a comprehensive report published by the United Nations Economic and Social Commission for Western Asia (UN-ESCWA) and the German Federal Institute for Geosciences and Natural Resources (BGR), with financial support from the German Federal Ministry for Economic Cooperation and Development (BMZ).